1. Field of the Invention
The present invention relates to a diode load driving power supply apparatus that supplies power to a plurality of diode loads in order to drive the diode loads.
2. Description of the Related Art
In Japanese Unexamined Patent Application Publication No. 2011-124195, there is disclosed a lighting circuit that lights a plurality of LEDs. The circuit described in Japanese Unexamined Patent Application Publication No. 2011-124195 has a configuration in which a DC-DC converter is provided for each of the plurality of LEDs. It is described that, with this configuration, a stable current is supplied to each of the LEDs and therefore lighting of the LEDs can be accurately controlled and the LEDs can be prevented from flickering, for example.
When a plurality of diode loads are controlled in a unified manner using a single controller in a state where there are variations between their forward drop voltages VF, a problem occurs in that an overshoot or rise delay is generated in the current rise characteristics at the time of start up. This is a problem that causes noise to be generated on the load side and affects the load-side characteristics when the LEDs are used as the light source of a projector, for example. In addition, if the overshoot becomes large, there is a risk that the rated current will be exceeded and the light source will be degraded. Since the forward drop voltage of the LEDs is not recognized or considered in Japanese Unexamined Patent Application Publication No. 2011-124195, this problem cannot be solved by Patent Japanese Unexamined Patent Application Publication No. 2011-124195.